It is well known that water-soluble chromate in cement gives rise to allergic reactions in workers subjected to contact with cement-containing products. In particular, construction workers who are subjected to regular skin contact with wet cement such as wet cement paste, wet mortar, and concrete mixes, have a risk of contracting chromate-related eczema.
It is known to reduce the content of water-soluble chromate in a cement composition by addition of ferrous sulphate. The ferrous sulphate may be added, e.g., during the preparation of cement-containing mixes or during manufacture of the cement, vide e.g. WO 82/02040. The iron(II) sulfate reduces Cr.sup.+6 to Cr.sup.+3, the latter having low solubility in cement-water mixes. The reaction between Fe.sup.+2 and Cr.sup.+6 takes place in aqueous solution, e.g. when water is added to a cement containing iron(II) sulfate.